Electric switch.



E. B. MERRIAM. ELECTRIC SWITCH.

-APPUCATION FILED 5.10.1914.

Patented Aug. 20, 1918.

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UNITED STATES PATENT- OFFICE.

EZRA B. MERRIAL I, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A. CORPORATION OF NEW YORK.

ELECTRIC SWITCH.

In electric switches of the usual type the circuit is interrupted under oil and the arc is formed in a comparatively large body of oil, which apparently does not exert its full arc extinguishing efl'ect until some time after the arc has formed. As a result, the arc is-not extinguished as quickly as it might be if the insulating fluid'were applied more promptly and in a more efficient manner. The object of my invention is to render switches of this general character more effi-' cient, and reliable. A further object is to improve switches of this character so that 'the circuit is interrupted more promptly than in switches of the types heretofore used. To this end, my invention comprises various improvements and modifications which will be hereinafter more fully described and pointed out with particularity in the appended claims.

My invention will best be understood in connection with the accompanying drawing,

in which, merely for purposes of illustration, I have shown some of the various forms in which my invention may be embodied and in which Figure 1 is a longitudinal section through the oil pot of one form of switch embodying one form of. my invention, certain parts being shown diagrammatically; Fig. 2 is a similar longitudinal section through the oil pot of a switch embodying another form of my invention; Fig. 3 is a longitudinal section through the 011 pot of a switch embodying still another form of my invention; and Fig. 4 is a longitudinal section through the oil pot of a switch in which certain modifications and variations of my invention are embodied.

In the particular form of switch shown in Fig. 1, an oil pot 1 of metal orifother suitable material is partially filled with oil or similar insulating fluid to the level indicated by the dotted line. The circuit is Specification of Letters Patent.

Patented Aug. 20,1918.

Application filed February 10, 1914. Serial No. 817,812.

interrupted pot beneath the surface of the oil by suitable cooperating contacts, such as a movable tubular contact 2, preferably extending into the oil pot through some suitable insulator in the top, and moved by. some suitable mechanism not shown into and out of engagement with a tubular stationary contact 3 secured in the bottom of the oil pot.

If the contacts 2 and 3 are separated while a large amount of energy is flowing through the switch an arc is formed betweenthem. In orderthat this are may be extinguished prompt-1y and efiectually I provide some suitable means for subjecting it at the instant of its formation to the cooling and disrupting action of the oil, and also, if considered desirable. for sweepin the arc gases and other products which form a conductin path between the contacts away from t e contacts into a region where they will not assist in maintaining the are. One way of securing this result in accordance with my invention is to maintain a rapidly moving stream of oil or other insulating fluid, so directed that the instant the contacts separate the arc gases are caught and swept along away from the contacts by the rapidly moving insulating fluid. Since this fluid is alread in motion when the arc first forms, there is 'no delay due to getting a quiescent body of oil in motion, and the arc is subjected from the first instant of its existence to the action of the moving oil. In accordance with my invention the rapidly moving current of oil adjacent the point where the arc originates may be secured and maintained in many different ways. In the particular arrangement shown in Fig. 1 the oil is kept in motion through the tubular contacts 2 and 3 by a circulating system comprising an outlet pipe 4 leading from the interior of the tubular contact 3 to the circulating pump 5, which may be of any suitable type, but is preferably a centrifugal pump. The oil reaching the pumpthrough the pi e 4 is delivered to the oil pot 1 throug a supply pipe 6 and thence flows through openings 7 into the tubular. contact 2 and through the tubular stationary contact 3 back to the pump.

In order still=further to confinethe in- I sulating fluid to the vicinity of the arc and to assist in sweeping thearc gases into the discharge tube 4, I may provide a bafiie or 55 the pump is divided into two branches, 11

partition 8 firmly mounted in the oilpot beneath 'the surface of the 011 and provided with a central opening 9 through WhlCh the tubular contact 2 passes with comparatively slight clearance. If necessary to avoid excessive pressure beneath the baflle 8, some circulation of oil through it may be ermitted by vents 10. Thisbarrier or baflib 8 also assists in extinguishing the are by confining the oil and directing it against the arc in case the arc holds until the movable contact 3 passes above the baffle 8, in which case the arc is confined by the walls of the opening 8 and is quickly extinguished by the rapidly moving oil.

In operation, when the sw1tch 1s closed, the pump 5 maintains a circulation of Oll or other suitable insulating fluid through the contacts 2 and 3. As the switch opens, the rush of fluid out of the open end of the contact 2 tends to tear the arc to pieces and at the same time the rush of oil, into and through the tubular contact 3 tends to malntain a film of fresh cool oil on the surface of the contact and to sweep the arc gasesaway from the upper edge of the contact 2 and into the tube 4, where they are mingled with oil and quickly cooled. Since the oil is in motion before the contacts separate, the fresh cool oil begins to flow over the surfaces of the contacts the instant the contacts separate. As a result, the arc is subjected very promptly to the cooling and are destroying action of the oil, and hence does not get an opportunity to persist or to attain any great magnitude. If, by any chance the arc should persist until the movable contact 2 passes above the baffle 8, the arc gases confined in the opening 9 are subjected to the action of a swiftly moving current of oil passing through the opening in a direction opposite that of the movement of the contact 2, so that the arc gases cannot follow the movable contact 2 and maintain the are between the two contacts. Furthermore, the oil beneath the baffle 8 is confined-- in the neighborhood of the stationary contact 3 and exerts a cooling action upon the arc gases. As a result of the action of the various parts of the switch, the arc is very quicklv extinguished and the circuit opened.

In the particular modification shown in Fig. 2 the principal parts are much the same as in Fig. l. The supply pipe from which discharge into the oilpot 1 from opposite sides, beneath a barrier or baffle comprising a metallic ring or plate 12 mounted in the oilpot beneath the surface of the oil and provided with a central opening through which the movable contact passes with slight clearance. Openings 13 near the tip of the movable contact 2 permit the oil to flow into the movable contact and thence through the faces of the contacts the instant they separate, thereby disrupting the arc and sweeping the arc gases into the outlet pipe 4. If the arc persists, a very'pronounced are extinguishing effect will occur when thelower end of the movable contact 2 passes through the metal plate 12. Possibly this effect is due to the metal plate confining the oil in the immediate vicinity of the arc, to the cooling action of the metal plate, or to some other action which is not fully understood. I do not wish to be restricted to any particular theory, but observation has shown that the metal plate 12 submerged in oil does exert a marked arc extinguishing effect, as an arc can be drawn through it only with the greatest difficulty.

I may also, in accordance with my invention, increase the efficiency of the switch and the promptness witlrwhich the arc is extinguished by providing suitable means for hindering the displacement of the oil from the immediate vicinity of the arc and for accentuating the cooling of the arc gases by the surrounding medium. I may also, if desired, so arrange the parts that in case the arc persists it will tend to break up into a number of arcs in series, all of which are subjected to a pronounced cooling and extinguishing action by the insulating fluid, and which are surrounded by conditions most unfavorable to the existence of an arc. For example, I may, as shown in Fig. 3, provide the oil pot l with cooperating contacts of any well known type, as for example, the stationary contact 14 and the movable rod contact 15 actuated by any suitable mechanism. For the purpose of throttling the arc and maintaining the insulating medium in the most effective relation to the arc, I prefer to mount in the oil pot beneath the surface of the oil a metal tube or ring, such as the short metal tube 16, in such a position that the movable con tact passes through it and therefore draws the arc through it if the arc persists. The size'of this tube may be varied as desired. As an example, I have obtained very good results with a metal tube about 1% inches internal diameter where the movable contact is a rodhaving a diameter of $3 inch.

It is exceedingly difficult to draw an arc,-

through such a metal tube submergedin oil, and therefore this tube is a very eflective aid in interrupting the circuit. This metallic tube 16 may if desired, be made comparatively long and of substantially uniform diameter throughout, or, as shown in 3, a number of shorter arc extinguishingfdevices or tubes, such as the short metallic tubes 16', 17 and 18, may be positioned along the path of movement .of the movable contact and concentric therewith, so that the arc is drawn through all of them in case it should persist. In such case I prefer to make the metallic rings or are extinguishing devices of different diameter, as shown in Fig. 3, where, for example, the ring 17 is considerably larger than either of the adjacent rings. I also prefer to so mount these metallic rings or are extinguishing devices that gaps are left between their adjacent ends so that if by anychance current should attempt to flow through the metal of the tubes 16, 17

and 18, the result would be the formation of a plurality of arcs in series. Owing to the difference in diameter of the rings these arcs would be more or less horizontal and therefore transverse to the direction of movement of the oil through the metal rings, as the effect of the oil in rupturing these arcs is great. The metallic rings or are extinguishing devices may be supported in the pot in any suitable way, preferably by spiders or arms 19 which do not offer much obstruction to the movement of oil in the pot.

To accentuate the arc. extinguishing properties of the switch embodying this particular form of my invention, I may provide means for maintaining a flow of insulating fluid over the contact surfaces so that fresh cool oil will be supplied rapidly and continuously to the arcing surfaces of the contacts at the instant the contacts separate. I prefer to maintain this current of oil or insulating fluid in a direction transverse to the longitudinal axis of the are so that the arc gases will be swept to one side and the are thereby weakened. As an example of one way in which this result may be accomplished, I have illustrated the pump 5 with its intake connected to the pipe 20, opening at one side of the oil pot and its discharge pipe 21 opening into the other side of the oil pot 1 in such a position that a strong current of oil flows directly across the bottom of the oilpot and across the surface of the stationary contact 14. As a result of this construction, any are that may tend to persist between the upper surface of the stationary contact 14 and either the end of the movable contact 15, or the lower edge of the metal are extinguishing tube 16 must resist the cooling and disruptive action of the rapidly moving current of oil or other insulating material.

When the switch is closed, the current of oil is flowing swiftly over the bottom of the oil pot 1. As the contacts separate, this current of oil instantly causes fresh cool oil to flow over the surfaces of the contacts and through the arc. As the movable contact rises, the arc, if it persists, is drawn into the first arc extinguishing device 16, where lateral movement of the oil away from the arc is hindered and where a pronounced cooling action is exerted 011 the are by the metal walls of the tube 16. As the contact 15 rises still further, the arc extinguishing action of the next metal ring 17 is exerted, and in addition, any movement of the oil in the metal rings will be in a direction to sweep the arc gases downward and away from the arc stream. If the arc breaks up into small arcs in series between the edges of the iron rings 16 and 17 these small arcs will be swept away and broken by the movement of the oil transverse to these small arcs. In very few cases will the arc persist long enough to reach into the arc extinguishing device 17, but if it should it will then be drawn into the arc'extinguishing tube or device 18, where it will surely be extinguished, particularly in view of the cooling and are destroying action of the current of oil over the bottom of the oil pot which is continuously throwing fresh cool oil over the arcing surface of the fixed contact 14. As a result of all these actions the switch will open a large amount of energy with a comparatively small amount of oil. and the resulting arc will be extinguished very' quickly and completely.

In Fig. 4 I have shown a form of my invention in which a strong arc confining tube 22 is mounted adjacent the contact 14 to form in effect a projection thereof concentric with the movable contact 15. Immediately above the upper end of the are confining tube 22 I may, if desired, mount arc extinguishing devices or rings 23- and 24 which surround the path of the movable contact, but are preferably set at an angle thereto, so that any fluid flowing through them will be deflected and directed across the path of the arc. These angularly set rings 23 and 24 are supported any suitable way,rpreferably on spiders or ribs 25. To further accentuate the are destroying and cooling properties of. the metal rings 23 and 24 I provide suitable means for maintainmg a current of oil or insulating fluid transverse the pot and preferably through the rings 23 and 24. One way of doing this is shown in Fig. 4, in which the pipe 26 leads from one side of the oil pot to the intake of the circulating pump 5, while the pipe 27 discharges into' the oil pot at a point between the widely separated edges of the rings 23 and 24. As'a result of this arrangement a strong current of oil is condrawn upward in the oil pot it passes into the ring 23 which exerts a cooling and extinguishing effect upon it, and also causes it to be subjected to a pronounced destroying action due to the direction of movement of the insulating fluid through the ring 23. A similar arc extinguishing action and the destruction of the arc in the opposite direction occurs if the arc persists long enough to be drawn into the upper arc extinguishingring 24, while at the same time the distorted arc is subjected to the destructive effects of the rapidly moving current of oil which is flowing from the pipe 27 through the oil pot and over the surfaces of the rings 23 and 2i into the pipe 26. As a result the arc is very quickly and thoroughly extinguished with a comparatively small amount of oil. a

My invention may be embodied in many other forms and I therefore do not wish to limit myself to the precise arrangement disclosed except in so far as it is limited by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the Fnited States, is

1. An electric switch comprising a vessel adapted to contain an insulating fluid, cooperating contacts separable beneath the surface of said fluid, and means for rapidly circulating said fluid through said vessel and over said contacts prior to and during the movement of said contacts to circuit opening position.

2. An electric switch comprising a vessel adapted to contain an insulating fluid, relativelyn'iovable cooperating contacts separable beneath the surface of said fluid, a plurality of separate open ended arc confining and extinguishing members spaced apart and mounted within the fluid in said vessel, each member having walls concentric with the path of movement of said contacts whereby the arc is drawn through said members as said contacts separate and thereby cooled and extinguished.

3. An electric switch comprising a Vessel adapted to contain an insulating fluid, a stationary contact within said vessel, a cooperating contact movable longitudinally of said vessel, and a plurality of separate metallic tubular arc extinguishing members open at each end and independently mounted beneath the fluid in said vessel to surround said movable contact when in switchclosing position whereby the are formed is drawn through said members as said con tacts separate.

l. An electric switch comprising a vessel adapted to contain an insulating fluid, a stationary contact atone end of said vessel, a plurality of separate metallic tubular arc confining members independently mounted beneath the fluid in said vessel, each of said members differing in bore from the adjacent member, and a cooperating contact movable through said members into and out of engagement with said stationary contact.

5. An electric switch comprising a vessel adapted to contain oil, a stationary contact in said vessel, a cooperating contact mounted to move into and out of engagement with said stationary contact, and separate annu-- lar arc extinguishing members independently mounted beneath the fluid in said vessel with their longitudinal axes in alinement with one another and with said stationary contact whereby the are formed as said contacts separate is successively drawn through said members and extinguished.

In witness whereof, I have hereunto set my hand this 5th day of February, 1914.

- EZRA B. MERRIAM.

Witnesses:

C. L. YORK, HELEN Oaronn. 

